1. Field of the Invention
The present invention relates to a vehicle disc brake used for vehicles such as automobiles and motorcycles, and specifically relates to a structure of a pad retainer configured to movably support lug pieces provided at a shoe of a friction pad by pad guide grooves formed in caliper supporting arms.
2. Description of the Related Art
In a conventional vehicle disc brake including lug pieces which are respectively projecting from both side portions of a shoe of a friction pad, the lug pieces are movably supported in pad guide grooves formed in caliper supporting arms of a caliper bracket, so that the friction pads are hung movably in a disc axis direction. In addition, a pad retainer formed of a thin metallic plate is interposed between the pad guide groove and the lug piece. The pad retainer is configured to guide a movement of the friction pad in the disc axis direction, and to return the friction pad from a side surface of a disc rotor when the braking is released.
Some of such pad retainers include a pair of retainer portions mounted in pad guide grooves, a connecting piece extending over an outer edge of a disc rotor so as to connect the pair of retainer portions together, and pad returning portions for biasing friction pads in a direction in which the friction pads move away from the disc rotor. Each retainer portion includes an outer side piece disposed along an outer side surface in a disc radial direction of the pad guide groove, a deep side piece disposed along an opposing surface, and an inner side piece inclining from an end portion of the deep side piece at an inner side in the disc radial direction outwards in the disc radial direction. Each pad returning portion includes: an elastic loop portion formed into an arc shape by bending a narrow elongated piece, which extends in a direction opposite to the disc rotor from an outer side in the disc radial direction of the deep side piece, and then back towards the disc rotor; and the pad returning portion formed of a narrow elongated piece, which extends from a bent-back end of the elastic loop portion in a direction of the disc rotor and gradually inclines in a direction opposite to the deep side piece (see, for example, JP-B 4713651).
The pad retainer in JP-B 4713651 described above is capable of returning the friction pads from side surfaces of the disc rotor by the pad returning portion when the braking is released, but is incapable of stably returning the friction pad in some cases because the pad returning portion is formed of the narrow elongated piece inclining in the direction opposite to the deep side piece.